1. Field of the Invention
The present invention relates to a wired circuit board and a connection structure between wired circuit boards. More particularly, the present invention relates to a wired circuit board suitably used as a relay flexible wiring circuit board electrically connected to a suspension board with circuit and an external board, and a connection structure between wired circuit boards.
2. Description of Related Art
Conventionally, the relay flexible wiring circuit board has been electrically connected to a suspension board with circuit and an external board to electrically relay them, and used in hard disk drives.
In such relay flexible wiring circuit board, from the viewpoint of transmission efficiency of electrical signals, impedance matching at connection points between the relay flexible wiring circuit board and the suspension board with circuit has been desired and various proposals for matching the impedance have been made.
For example, it has been proposed that a relay flexible wiring circuit board is constructed with two wired circuit boards including a first wired circuit board connected with a suspension board with circuit and mounted with a preamplifier IC and a second wired circuit board connected to the first wired circuit board and to an external board, in which the lamination of the first wired circuit board and the lamination of the suspension board with circuit are made identical (cf. Japanese Unexamined Patent Publication No. 2004-363331).
According to the relay flexible wiring circuit board described in Japanese Unexamined Patent Publication No. 2004-363331, since the lamination of the suspension board with circuit is identical to that of the first wired circuit board, impedance matching at connection points between the suspension board with circuit and the first wired circuit board can be achieved. As a result, electrical signals between a magnetic head mounted on the suspension board with circuit and the preamplifier IC mounted on the first wired circuit board can be efficiently transmitted.